1. Field of the Invention
This invention relates to transmission apparatus, in particular for a motor vehicle, of the type in which at least one pinion, mounted for free rotation on a shaft, is associated with controlled means for coupling the shaft and pinion for rotation together, the said means comprising at least one one-way locking mechanism mounted between the shaft and the pinion, together with means for actuating the said mechanism.
2. Description of Related Art
It has previously been proposed, in Applications FR 0 002 482 and FR 0 003 491 of the Applicant, to provide an automatic transmission of the gear type for a motor vehicle which comprises two clutches coupling the output shaft of an internal combustion engine with two input shafts of the transmission, driving pinions mounted on the said input shafts, driven pinions mounted on the output shaft of the transmission and in engagement with the driving pinions, and with them defining transmission ratios, one of the pinions of each ratio being coupled in rotation to its shaft while the other one is free to rotate on its shaft and is associated with control means for coupling it with the shaft, for engagement of the corresponding transmission ratio.
The coupling means associated with each free pinion comprise two one-way locking mechanisms which are mounted in opposite directions between the free pinion and its shaft, while actuating means of these mechanisms enable them to be selectively rendered active or inactive.
In one embodiment of such a transmission, the one-way locking mechanisms are arranged on the flanks of the free pinions, and comprise locking members such as catches, which are associated with return springs and with pushers for engaging on sets of teeth formed on the flanks of the free pinions, or to move away from these teeth. Cams, mounted for example inside the shaft and carrying the free pinions, are connected to an actuator through an axial rod and are able to act on the pushers so as to put the catches into engagement with the teeth on the flanks of the pinions.